1. Field of the Invention
The present invention relates to a technique of controlling a return to game machines for pachisio game (Japanese slot game), pachinko game (pinball game), etc.
2. Description of Related Art
Generally, a game machine for pachisio game, pachinko game, etc. is constructed so that a game is started when a player throws a game medium such as medal, in the game machine, and that the game medium is paid out according to the winning state (style) occurred during the game.
This game machine generates a winning state, being called “big prize,” at a preset probability. Therefore, the player performs a game in expectation of a big prize on the game machine that the player is currently playing.
The game machine that produces a prize depending on the probability as described does not always produce the prize at a fixed probability. That is, it is constructed so as to converge on a preset probability when a significant number of games are digested. Therefore, (i) a prize occurs on a player performing even a small number of games, and (ii) a prize is not always guaranteed to a player despite he is performing a large number of games. With the game machine of this type, gambling characteristics can be enhanced to make the game more amusing. On the other hand, the player waiting for a prize for a long time might lose enthusiasm for the game. This leads to a tendency to miss the player (customer).
In order to solve the above circumstances, a variety of game machines have been proposed.
In a game machine disclosed in laid-open Japanese Patent Unexamined Publication No. 8-24401, there are provided two probability tables for controlling the probability of generating a big prize. In the case that the player performs a large number of games and gets tired of waiting for a prize, one of the two probability tables that has a higher probability is selected for change, thereby increasing the probability of generating the prize.
Laid-open Japanese Patent Unexamined Publication Nos. 6-79051 and 11-253640 have proposed game machines employing such means, being called “return.” The term “return” means a system that when predetermined conditions are satisfied, a game medium (e.g., medal) is paid out per game machine, depending on the amount of medals that a player threw in. A return type game machine of the former further increases game characteristics by controlling the return rate as a basis for payout of game media. On the other hand, a return type game machine of the latter adjusts the probability of generating a prize in consideration of the profit rate in the game center and the return rate to each game machine.
In the game machine according to the above Publication No. 8-24401, unevenness in the probability of generating a prize can be eliminated, whereas it has poor gambling characteristics. Therefore, players are less amused by the game.
In the game machines disclosed in the above Publication Nos. 6-79051 and 11-253640, unfairness can be removed by eliminating unevenness in the probability of generating a prize per game machine, whereas it has poor gambling characteristics. Therefore, players are less amused by the game.
Meanwhile, as a technique of increasing gambling characteristics, there is the so-called “jackpot”. The term “jackpot” means such a system of holding part of credits thrown in a plurality of game machines installed in a game center and then releasing the credit held in a certain game machine of the game center under predetermined conditions.
In the conventional jackpot, the probability of executing such a release to a game machine is extremely low although gambling characteristics can be increased. Therefore, because of this extremely low probability of release, the abovementioned problem is not yet solved insofar as eliminating unevenness of the probability of generating a prize.